Question

如何在Swift＆amp;中为折线和多边形添加注释。 MapKit？ By Point很简单。

Answer 1

S上。，

我不确定你在这里问的是什么，但我想你想在折线上的某处显示一个注释。

首先介绍如何获取折线：因此，假设您有一个CLLocation对象数组，它们将在地图上绘制折线。我们称这个位置对象数组：myLocations，它的类型为[CLLocation]。现在你应用程序中的某个地方调用了一个创建折线的方法，我们称之为createOverlayObject（locations：[CLLocation]） - ＆gt; MKPolyline。

您的电话可能如下所示：

let overlayPolyline = createOverlayObject(myLocations)

您调用的方法可能如下所示：

func createOverlayObject(locations: [CLLocation]) -> MKPolyline {
    //This method creates the polyline overlay that you want to draw.
    var mapCoordinates = [CLLocationCoordinate2D]()

    for overlayLocation in locations {

        mapCoordinates.append(overlayLocation.coordinate)
    }

    let polyline = MKPolyline(coordinates: &mapCoordinates[0], count: mapCoordinates.count)

    return polyline
}

这是第一部分，不要忘记实现mapView（_：rendererForOverlay overlay :)以获取渲染的线条。这部分看起来像这样：

func mapView(mapView: MKMapView, rendererForOverlay overlay: MKOverlay) -> MKOverlayRenderer {
    //This function creatss the renderer for the polyline overlay. This makes the polyline actually display on screen.
    let renderer = MKPolylineRenderer(overlay: overlay)
    renderer.strokeColor = mapLineColor //The color you want your polyline to be.
    renderer.lineWidth = self.lineWidth

    return renderer
}

现在第二部分在地图上的某处获得注释。如果您知道要将注释放在哪里，那么这实际上是直截了当的。假设您已经定义了一个名为myNiceMapView的地图视图，那么创建和显示注释会很简单：

func createAnnotation(myCoordinate: CLLocationCoordinate2D) {
    let myAnnotation = MKPointAnnotation()
    myAnnotation.title = "My nice title"
    startAnnotation.coordinate = myCoordinate

    self.myNiceMapView.addAnnotations([myAnnotation])
}

不要忘记实现mapView（_：MKMapView，viewForAnnotation annotation :) - ＆gt; MKAnnotationView？方法，可能看起来像：

func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? {
    //This is the mapview delegate method that adjusts the annotation views.

    if annotation.isKindOfClass(MKUserLocation) {

        //We don't do anything with the user location, so ignore an annotation that has to do with the user location.
        return nil
    }

    let identifier = "customPin"
    let trackAnnotation = MKAnnotationView.init(annotation: annotation, reuseIdentifier: identifier)

    trackAnnotation.canShowCallout = true

    if annotation.title! == "Some specific title" { //Display a different image
        trackAnnotation.image = UIImage(named: "StartAnnotation")
        let offsetHeight = (trackAnnotation.image?.size.height)! / 2.0
        trackAnnotation.centerOffset = CGPointMake(0, -offsetHeight)
    } else { //Display a standard image.
        trackAnnotation.image = UIImage(named: "StopAnnotation")
        let offsetHeight = (trackAnnotation.image?.size.height)! / 2.0
        trackAnnotation.centerOffset = CGPointMake(0, -offsetHeight)
    }

    return trackAnnotation
}

现在的挑战是找到正确的坐标放置注释的位置。我找不到比你有一个引用你想要放置注释的位置的CLLocationCoordinate2D更好的东西。然后使用for-in循环找到要放置注释的位置，如下所示：

for location in myLocations {

  if (location.latitude == myReferenceCoordinate.latitude) && (location.longitude == myReferenceCoordinate.longitude) {
    self.createAnnotation(location: CLLOcationCoordinate2D)
  }
}

希望这能回答你的问题。

如何向MKPolyline＆amp;添加描述MKPolygon？

1 个答案: